/*
 * We will display an alert if the user is accessing PODD with IE6 or below */
function displayBrowserAlert() {
    var browserVersion = getInternetExplorerVersion();
    if (navigator.appName == "Microsoft Internet Explorer" && browserVersion <= 6) {
      alert("PODD does not support Internet Explorer version 6 or below ! \n\n" +
            "It is recommended that you use another browser or upgrade your copy of Internet Explorer.");
    }
}

/*
 * What version of internet explorer are we dealing with ? */
function getInternetExplorerVersion() {
    var rv = -1; // Return value assumes failure.
    if (navigator.appName == 'Microsoft Internet Explorer') {
        var ua = navigator.userAgent;
        var re = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");
        if (re.exec(ua) != null)
            rv = parseFloat(RegExp.$1);
    }
    return rv;
}


/*
 * Write the string shortened to the given length, including only whole words. */
function writeAbstractWholeWords(inputStr, length) {
	
	// if string is less than the given length the whole string should be written
	var endChar = length - 1;
	// if string is less than 200 character long write the given string
	if (inputStr.length > length) {
		// get the closest whole word to the given length
		while (inputStr.charAt(endChar) != " ") {
			endChar--;
		}
	}
	document.write(inputStr.substring(0, endChar));
}


/*
 * Validate administration - create new user form */
function createUserFormValidator(){
	var validUserId = true;
	// only the create user page allows us to set the user name
	document.getElementById('errorUserName').innerHTML = '';
	var userName = document.getElementById('userName');
	if(isEmptyField(userName) || !isMinimumLength(userName, 6) || !isValidUserId(userName)){
		validUserId = false;
		document.getElementById('errorUserName').innerHTML = 'User name must be at least 6 characters';
	}
	var validInput = validateUserInfo();
	var validPassword = validateUserPassword();
	return validUserId && validInput && validPassword;
}
/*
 * Validate the users data fields (except password) */
function validateUserInfo(){

	var validInput = true;

	// reset the error message fields to empty string
	document.getElementById('errorEmail').innerHTML = '';
	document.getElementById('errorFirstName').innerHTML = '';
	document.getElementById('errorLastName').innerHTML = '';
	document.getElementById('errorOrganisation').innerHTML = '';
	document.getElementById('errorPhone').innerHTML = '';
	document.getElementById('errorAddress').innerHTML = '';

	// fields requiring validation
	var email = document.getElementById('email');
	var firstName = document.getElementById('firstName');
	var lastName = document.getElementById('lastName');
	var organisation = document.getElementById('organisation');
	var phone = document.getElementById('phone');
	var address = document.getElementById('address');

	// Check each input in the order that it appears in the form
	if(isEmptyField(email) || !isValidEmail(email)){
		validInput = false;
		document.getElementById('errorEmail').innerHTML = 'Please enter a valid e-mail address';
	}

	if(isEmptyField(firstName)){
		validInput = false;
		document.getElementById('errorFirstName').innerHTML = 'Required field';
	}

	if(isEmptyField(lastName)){
		validInput = false;
		document.getElementById('errorLastName').innerHTML = 'Required field';
	}

	if(isEmptyField(organisation)){
		validInput = false;
		document.getElementById('errorOrganisation').innerHTML = 'Required field';
	}

	if(isEmptyField(phone)){
		validInput = false;
		document.getElementById('errorPhone').innerHTML = 'Required field';
	}

	if(isEmptyField(address)){
		validInput = false;
		document.getElementById('errorAddress').innerHTML = 'Required field';
	}

	return validInput;
}

/* 
 * Validate the users password */
function validateUserPassword(){
	
	var validInput = true;
	
	// reset the error message fields to empty string
	document.getElementById('errorPassword').innerHTML = '';
	document.getElementById('errorConfirmPassword').innerHTML = '';

	// fields requiring validation
	var password = document.getElementById('password');
	var confirmPassword = document.getElementById('confirmPassword');
	
	// Check each input in the order that it appears in the form
	if(isEmptyField(password) || !isMinimumLength(password, 6) || !isNonSpaceCharater(password)){
		validInput = false;
		document.getElementById('errorPassword').innerHTML = 'Password must be at least 6 characters with no spaces';
	}
	if(confirmPassword.value != password.value){
		validInput = false;
		document.getElementById('errorConfirmPassword').innerHTML = 'Passwords must match';
	}
	return validInput;
}

function valiadateDescription() {
    var valid = true;
    var address = document.getElementById('object_description');
    // Check each input in the order that it appears in the form
    if(isEmptyField(address)){
        document.getElementById('errorDescription').innerHTML = 'Description can not be empty.';
        valid = false;
    }
    return valid;
}


/* ----- functions to validate form fields ----- */

/* check the element's string is empty */
function isEmptyField(elem){
	if(elem.value.length == 0){
		return true;
	}
	return false;
}

/* check the element's string has at least the minimum length */
function isMinimumLength(elem, length){
	if(elem.value.length >= length){
		return true;
	}
	return false;
}

/* check the element's string contains only numbers and letters */
function isAlphanumeric(elem){
	var alphaExp = /^[0-9a-zA-Z]+$/;
	if(elem.value.match(alphaExp)){
		return true;
	}	
	return false;
}

/* check the element's string contains a valid email address */
function isValidEmail(elem){
	var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;
	if(elem.value.match(emailExp)){
		return true;
	}
	return false;
}

/* check the element's string contains a valid user name */
function isValidUserId(elem){
	var userIdExp = /[\w-_\.]+/;
	if(elem.value.match(userIdExp)){
		return true;
	}
	return false;
}

/* check the element's string is between the minimum and maximum length */
function lengthRestriction(elem, min, max){
	var userInput = elem.value;
	if(userInput.length >= min && userInput.length <= max){
		return true;
	}
	return false;
}

/* check the element's string is all numbers */
function isNumeric(elem){
	var numericExpression = /^[0-9]+$/;
	if(elem.value.match(numericExpression)){
		return true;
	}
	return false;
}

/* check the element's string is all letters */
function isAlphabet(elem){
	var alphaExp = /^[a-zA-Z]+$/;
	if(elem.value.match(alphaExp)){
		return true;
	}
	return false;
}

function isNonSpaceCharater(elem){
	var alphaExp = /^[^\s]+$/;
	if(elem.value.match(alphaExp)){
		return true;
	}
	return false;
}